Ju-Won Song Kyu-Young Whang Young-Koo Lee Sang-Wook Kim The clustering Property of Corner Transformation for Spatial Database Applications. 28-35 1999 conf/compsac/1999 COMPSAC http://computer.org/proceedings/compsac/0368/03680028abs.htm db/conf/compsac/compsac1999.html#SongWLK99